Ryanair has carried 10 million passengers on its London Stansted-Dublin route since operations began in June 1989.
The low fares airline now operates 24 daily flights which will carry 1.5m passengers this year.
To mark the occasionn Ryanair has announced a 250,000 seat sale for £1.00 (€1.48).
Head of Communications, Paul Fitzsimmons said today:"Ryanair has revolutionised travel between London and Dublin, one of Europe’s busiest air routes.
"Since we commenced flying from London Stansted to Dublin in 1989, an amazing 10 million ordinary consumers have saved over £1bn, (€1.48bn)," he added.